The labs at LIGO-MIT are dedicated to advancing precision measurement techniques aimed at improving future gravitational wave detectors. The two dominant noise mechanisms which limit optical precision measurement derive from the quantum nature of light (quantum noise), and from the thermal motion of molecules in our measurement devices (thermal noise).
The quantum nature of light presents a limit to the precision of optical measurements. In the case of a gravitational wave detector, this limit can be understood in terms of the counting statistics associated with photons, or equivalently in terms of the zero-point energy of the electro-magnetic field. We are working to reduce the “quantum noise” in Advanced LIGO by preparing entangled photon pairs that can be injected into the detector.
Modern precision measurements operate on such minute length scales that random thermal motion of molecules in the instrument can be a limiting source of noise. Thermal noise can be reduced directly by lowering the temperature of the instrument (cryogenics), or somewhat less directly by careful construction and material choice. We are researching special materials that may help future gravitational wave detectors operate with reduced thermal noise.